Narrative:

After a request for hems operation to a scene; weather reporting indicated ceilings were 1;000-2;000 ft; visibility well above VFR along the three intended routes of flight. After patient loading; second leg was begun. Weather conditions enroute required slight deviations to avoid areas where the visibility decreased along the intended course. As the flight progressed; deviations around the areas of restricted visibility became more difficult and the ceiling less well defined. Encountering 3-5 miles hazy visibility was adequate to continue; but conditions were not what were expected. Suddenly visibility was less than three miles and loss of visual reference with the surface appeared imminent. Company inadvertent instrument meteorological conditions procedure was initiated with a climb and transition to instrument flight. After climb to minimum safe altitude; approach was contacted to declare an emergency and to request an IFR clearance and approach. With vectors to the ILS approach. Helicopter safely landed at the airport. Being somewhat new to operating in this area I expected to learn more about how weather acts here over time. However; conversations with pilots who have operated in this area for years reveal this weather can be tricky and unpredictable. Many of the weather reporting facilities are at airfields down in valleys. This is adequate for IFR airplane operations from runways to runways. Weather observations taken from more of the hill tops and less spread out would be helpful to helicopters that operate VFR close to the ground and off airport. For now the best practice to avoid recurrence would be a more conservative approach to weather/launch decisions.

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Original NASA ASRS Text

Title: EMS helicopter pilot encounters IMC during return flight from a scene. An IFR climb to the MSA is initiated and ATC is contacted for an IFR clearance to the destination airport.

Narrative: After a request for HEMS operation to a scene; weather reporting indicated ceilings were 1;000-2;000 FT; visibility well above VFR along the three intended routes of flight. After patient loading; second leg was begun. Weather conditions enroute required slight deviations to avoid areas where the visibility decreased along the intended course. As the flight progressed; deviations around the areas of restricted visibility became more difficult and the ceiling less well defined. Encountering 3-5 miles hazy visibility was adequate to continue; but conditions were not what were expected. Suddenly visibility was less than three miles and loss of visual reference with the surface appeared imminent. Company Inadvertent Instrument Meteorological Conditions procedure was initiated with a climb and transition to instrument flight. After climb to minimum safe altitude; Approach was contacted to declare an emergency and to request an IFR clearance and approach. With vectors to the ILS approach. Helicopter safely landed at the airport. Being somewhat new to operating in this area I expected to learn more about how weather acts here over time. However; conversations with pilots who have operated in this area for years reveal this weather can be tricky and unpredictable. Many of the weather reporting facilities are at airfields down in valleys. This is adequate for IFR airplane operations from runways to runways. Weather observations taken from more of the hill tops and less spread out would be helpful to helicopters that operate VFR close to the ground and off airport. For now the best practice to avoid recurrence would be a more conservative approach to weather/launch decisions.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.